Centrifugal air-oil separator

ABSTRACT

A centrifugal air-oil separator for separating liquid particles from gases containing the liquid particles includes a substantially cylindrical air-oil separation chamber and a substantially conical liquid discharge chamber which are integrated with each other and are horizontally disposed, and an air-oil separation plate disposed between a gas supply port communicating with the air-oil separation chamber and a gas discharge port communicating with the liquid discharge chamber. A liquid discharge port is provided at a lowest portion between a largest-diameter portion of the liquid discharge chamber and the air-oil separation plate, and the liquid discharge port is covered thereabove with a reverse flow prevention wall. A strong swirl flow is generated in the air-oil separation chamber by the action of the air-oil separation plate to thereby enhance the liquid separation effect, and the reverse flow of liquid from the liquid discharge port to the liquid discharge chamber can be prevented.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a centrifugal air-oil separatordisposed horizontally and including integrally a substantiallycylindrical air-oil separation chamber and a substantially conicalliquid discharge chamber.

2. Description of the Related Art

Centrifugal air-oil separators are already known to the public through,for example, JP-A-11-264312. A centrifugal air-oil separator disclosedin this Japanese Unexamined Patent Publication is designed to separateoil mist from blow-by gases of an engine and includes an upper air-oilseparation chamber and a lower liquid discharge chamber which aredisposed with their axes being oriented vertically. When blow-by gasescontaining oil mist is supplied into the interior of the cylindricalair-oil separation chamber which is situated at an upper position in atangential direction, a swirl flow is generated, and oil mist separatedradially outwardly by virtue of centrifugal force is discharged from alower end of the conical liquid discharge chamber which is situated at alower position, whereas the blow-by gases from which the oil mist wasseparated is discharged upwardly from the center of the air-oilseparation chamber.

While the conventional centrifugal air-oil separator is verticallydisposed with the axes of the air-oil separation chamber and the liquiddischarge chamber being oriented vertically, there sometimes occurs anecessity to dispose the centrifugal air-oil separator horizontally dueto the limitation to the mounting space. Even when this occurs,separated liquid must be discharged from the liquid discharge chamber ina smooth fashion.

SUMMARY OF THE INVENTION

The prevent invention was made in view of the situations and an objectthereof is to enable the smooth discharge of separated liquid even inthe event that the centrifugal air-oil separator is disposedhorizontally.

With a view to attaining the object, according to a first aspect of theinvention, there is provided a centrifugal air-oil separator including:a substantially cylindrical air-oil separation chamber and asubstantially conical liquid discharge chamber which are integrated witheach other and horizontally disposed; and an air-oil separation platedisposed between a gas supply port communicating with-the air-oilseparation chamber and a gas discharge port communicating with theliquid discharge chamber, wherein a liquid discharge port is provided ata lowest portion between a largest-diameter portion of the liquiddischarge chamber and the air-oil separation plate.

According to the construction, since the air-oil separation plate isdisposed between the gas supply port communicating with the air-oilseparation chamber and the gas discharge port communicating with theliquid discharge chamber, the liquid separation effect can be enhancedby generating a strong swirl flow within the air-oil separation chamberthrough prevention of short-circuiting between the gas supply port andthe gas discharge port, and the reverse flow of liquid from the liquiddischarge port to the air-oil separation chamber can also be prevented.Moreover, since the liquid discharge port is provided at the lowestportion between the largest-diameter portion of the liquid dischargechamber and the air-oil separation plate, liquid adhering to theinterior wall of the air-oil separation chamber and the liquid dischargechamber can be guided into the liquid discharge port by gravity forsmooth discharge therefrom. Thus, since the separated liquid can bedischarged smoothly even when the centrifugal air-oil separator isdisposed horizontally, the degree of freedom in the layout of thecentrifugal air-oil separator can largely be enhanced.

According to a second aspect of the invention, there is provided acentrifugal air-oil separator as set forth in the first aspect of theinvention, wherein a reverse flow prevention wall is provided above theliquid discharge port.

According to the construction, since the reverse flow prevention wall isprovided above the liquid discharge port, the reverse flow of liquidfrom the liquid discharge port to the liquid discharge chamber caneffectively be prevented.

According to a third aspect of the invention, there is provided acentrifugal air-oil separator as set forth in the second aspect of theinvention, wherein the reverse flow prevention wall is provided at alower portion within the liquid discharge chamber in such a manner as tofollow a swirl flow to connect to an interior wall of the liquiddischarge chamber on a more upstream side of the swirl flow than theliquid discharge port.

According to the construction, since the reverse flow prevention wall isformed at the lower portion within the liquid discharge chamber in sucha manner as to follow the swirl flow, the influence imposed on the swirlflow by the reverse flow prevention wall can be restrained to a minimumlevel. In addition, since the reverse flow prevention wall connects tothe interior wall of the liquid discharge chamber on the more upstreamside of the swirl flow than the liquid discharge port, the generation ofnegative pressure that would draw liquid out of the liquid dischargeport can be prevented by avoiding the direct action of the swirl flow onthe liquid discharge port.

According to a fourth aspect of the invention, there is providedcentrifugal air-oil separator as set forth in the third aspect of theinvention, wherein a liquid discharge passage is provided on a moredownstream side of the swirl flow than the liquid discharge port betweenthe interior wall of the liquid discharge chamber and the reverse flowprevention wall.

According to the construction, since the liquid discharge port isprovided on the more downstream side of the swirl flow than the liquiddischarge port and between the interior wall of the liquid dischargechamber and the reverse flow prevention wall, the liquid adhering to theinterior wall of the air-oil separation chamber and the liquid dischargechamber can be guided into the liquid discharge port without anyproblem.

According to a fifth aspect of the invention, there is provided acentrifugal air-oil separator as set forth in the first aspect of theinvention, wherein the reverse flow prevention wall is formed integrallywith the liquid discharge chamber in such a manner as to extend from theliquid discharge chamber substantially in parallel with an axis of theair-oil separation chamber.

According to the construction, since the reverse flow prevention wallformed integrally with the liquid discharge chamber extends from theliquid discharge chamber substantially in parallel with the axis of theair-oil separation chamber, the reverse flow prevention wall can beformed without increasing the number of components. Moreover, since thereverse flow prevention wall can be formed at the same time as theair-oil separation chamber and the liquid discharge chamber are formed,the formation of the reverse flow prevention wall can be facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a centrifugal air-oilseparator;

FIG. 2 is a cross-sectional view taken along the line 2—2 in FIG. 1;

FIG. 3 is a cross-sectional view taken along the line 3—3 in FIG. 1; and

FIG. 4 is a sectional view taken along the line 4—4 in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A mode for carrying out the invention will be described based on anembodiment illustrated in FIGS. 1 to 4.

A centrifugal air-oil separator according to the invention is designedto separate liquid particles contained in gases from the gases utilizingthe principle of a cyclone device. The air-oil separator includes acylindrical housing 11, a conical housing 12 integrally connecting to aright end of the cylindrical housing 11 and an end plate 13 which closesa left end of the cylindrical housing 11. The cylindrical housing 11 andthe conical housing 12 are disposed with an axis L of the separatorbeing oriented horizontally. A gas discharge pipe 14 situated on theaxis L penetrates through the end plate 13 and a disk-like air-oilseparation plate 15 is fixed to an outer circumference of the gasdischarge pipe 14. The air-oil separation plate 15 is situated slightlyleftward of a boundary between the cylindrical housing 11 and theconical housing 12, so that an air-oil separation chamber 16 ispartitioned on the left-hand side of the air-oil separation plate 15,whereas a liquid discharge chamber 17 is partitioned on the right-handside of the same plate 15. The air-oil separation chamber 16 and theliquid discharge chamber 17 communicate with each other via a gap αformed along an outer circumference of the air-oil separation plate 15.

A gas supply pipe 18 is connected to the air-oil separation chamber 16at a position close to the end plate 13, and a gas supply port 19 of thegas supply pipe 18 opens in an interior wall of the air-oil separationchamber 16 in a tangential direction (refer to FIG. 2). A gas dischargeport 20 formed in the interior of the gas discharge pipe 14 opens to theliquid discharge chamber 17. A liquid discharge port 22 of a liquiddischarge pipe 21 communicates with a lowest portion of alargest-diameter portion of the liquid discharge chamber 17 or aboundary with the air-oil separation chamber 16. The liquid dischargeport 22 is covered thereabove with a reverse flow prevention wall 23extending integrally from an interior surface of the conical housing 12.An interior wall of the cylindrical housing 11 and the conical housing12 and an end portion of the reverse flow prevention wall 23 areconnected to each other via a partition wall 24 on an upstream side of aswirl flow generated in the interior of the liquid discharge chamber 17,and a liquid discharge passage 25 is formed on a downstream side of theswirl flow between the interior wall of the cylindrical housing 11 andthe conical housing 12 and the other end portion of the reverse flowprevention wall 23 (refer to FIG. 3).

Thus, since the reverse flow prevention wall 23 is formed integrallywith the liquid discharge chamber 17 and, moreover, extends from theliquid discharge chamber 17 toward the air-oil separation chamber 16substantially in parallel with the axis L, the reverse flow preventionwall 23 can be formed integrally with the cylindrical housing 11 and theconical housing 12 at the same time as both the housings are, forexample, die cast without complicating the construction of a mold,whereby molding of the reverse flow prevention wall 23 can befacilitated without increasing the number of components.

Next, the function of the embodiment of the invention which isconstructed as has been described above will be described.

When gases containing liquid particles which is supplied from the gassupply pipe 18 passes through the gas supply port 19 to flow into theair-oil separation chamber 16 of the centrifugal air-oil separator,since the gas supply port 19 opens in the interior wall of the air-oilseparation chamber 16 in the tangential direction, a swirl flow isgenerated in such a manner as to surround the circumference of the gasdischarge pipe 14, and liquid particles contained in the gases arediffused radially outwardly by virtue of centrifugal force and adhere tothe interior wall of the air-oil separation chamber 16. As this occurs,since the air-oil separation plate 15 is interposed between the air-oilseparation chamber 16 and the liquid discharge chamber 17,short-circuiting between the gas supply port 19 and the gas dischargeport 20 can be prevented. Further, since the gas discharge pipe 14protruding on the axis L of the air-oil separation chamber 16constitutes a guide member for a swirl flow, it is possible to generatea strong swirl flow within the interior of the air-oil separationchamber 16 to thereby enhance the liquid separation effect. Moreover,since the air-oil separation plate 15 is supported by making use of thegas discharge-pipe 14, the necessity is obviated of a special supportmember for supporting the air-oil separation plate 15.

Gases that have flowed from the air-oil separation chamber 16 into theliquid discharge chamber 17 after passing through the gap α formedaround the circumference of the air-oil separation plate 15 swirlsfurther therein, and liquid particles separated from the gases withinthe liquid discharge chamber 17 adhere to the interior wall of theliquid discharge chamber 17. The gases from which liquid was separatedis then discharged into the gas discharge port 20 which opens to theliquid discharge chamber 17. Then, liquid adhering to the interior wallof the air-oil separation chamber 16 and liquid adhering to the surfacesof the gas discharge pipe 14 and the air-oil separation plate 15 flowdownward or fall by gravity to collects at a bottom portion of theair-oil separation chamber 16 and is then discharged therefrom into theliquid discharge port 22 provided in the lowest portion of the liquiddischarge chamber 17. Further, liquid adhering to the interior wall ofthe liquid discharge chamber 17 flows down by gravity along an inclinedinner wall of the conical housing 12 and is then discharged therefrominto the liquid discharge port 22 provided in the lower portion of theliquid discharge chamber 17.

When the flow rate of gases passing through the centrifugal air-oilseparator increases and the swirl flow within the liquid dischargechamber 17 is strengthened, there occurs a tendency that liquid withinthe liquid discharge port 22 is drawn out into the liquid dischargechamber 17 by virtue of a negative pressure acting on the opening of theliquid discharge port 22. However, since the liquid discharge port 22 iscovered thereover with the reverse flow prevention wall 23 which extendsto follow in the flowing direction of the swirl flow and the end portionof the reverse flow prevention wall 23 and the interior wall of thecylindrical housing 11 is connected by the partition wall 24 on theupstream side of the swirl flow, not only can the influence imposed onthe swirl flow by the reverse flow prevention wall 23 be restrained to aminimum level but also the generation of negative pressure which causesliquid to reverse from the liquid discharge port 22 can be restraineddue to the swirl flow not acting directly on the opening of the liquiddischarge port 22. In addition, even if liquid reverses from the liquiddischarge port 22, the liquid is blocked by the reverse flow preventionwall 23 to thereby be prevented from flowing into the liquid preventionchamber 17. Furthermore, even if as light amount of liquid reverses intothe liquid discharge chamber 17, the liquid is blocked by the air-oilseparation plate 15 to thereby be prevented from reversing into theair-oil separation chamber 16. In addition, since the liquid dischargepassage 25 is formed at the other end portion of the reverse flowprevention wall 23 on the downstream side of the swirl flow, the liquidthat has collected along the interior wall of the air-oil separationchamber 16 and the liquid discharge chamber 17 can flow into the liquiddischarge port 22 without any problem.

As has been described heretofore, even if the centrifugal air-oilseparator, which used to be disposed vertically, is disposedhorizontally, since liquid separated from gases can be discharged fromthe liquid discharge chamber 17 smoothly, the degree of freedom in thelayout of the centrifugal air-oil separator can largely be enhanced.

While the embodiment of the invention has been described in detail asabove, the design of the invention may be modified variously withoutdeparting from the sprit and scope of the invention.

For example, while with the centrifugal air-oil separator according tothe embodiment, the axis L thereof is disposed horizontally, the axis Ldoes not have to be disposed perfectly horizontally but may be inclinedslightly.

While the centrifugal air-oil separator according to the invention iseffective in separating oil mist from blow-by gases from the engine, theseparator can be used for any other applications.

Thus, according to the first aspect of the invention, since the air-oilseparation plate is disposed between the gas supply port communicatingwith the air-oil separation chamber and the gas discharge portcommunicating with the liquid discharge chamber, the liquid separationeffect can be enhanced by generating a strong swirl flow within theair-oil separation chamber through prevention of short-circuitingbetween the gas supply port and the gas discharge port, and the reverseflow of liquid from the liquid discharge port to the air-oil separationchamber can also be prevented. Moreover, since the liquid discharge portis provided at the lowest portion between the largest-diameter portionof the liquid discharge chamber and the air-oil separation plate, liquidadhering to the interior wall of the air-oil separation chamber and theliquid discharge chamber can be guided into the liquid discharge port bygravity for smooth discharge therefrom. Thus, since the separated liquidcan be discharged smoothly even when the centrifugal air-oil separatoris disposed horizontally, the degree of freedom in the layout of thecentrifugal air-oil separator can largely be enhanced.

According to the second aspect of the invention, since the reverse flowprevention wall is provided above the liquid discharge port, the reverseflow of liquid from the liquid discharge port to the liquid dischargechamber can effectively be prevented.

According to the third aspect of the invention, since the reverse flowprevention wall is formed at the lower portion within the liquiddischarge chamber in such a manner as to follow the swirl flow, theinfluence imposed on the swirl flow by the reverse flow prevention wallcan be restrained to a minimum level. In addition, since the reverseflow prevention wall connects to the interior wall of the liquiddischarge chamber on the more upstream side of the swirl flow than theliquid discharge port, the generation of negative pressure that woulddraw liquid out of the liquid discharge port can be prevented byavoiding the direct action of the swirl flow on the liquid dischargeport.

According to the fourth aspect of the invention, since the liquiddischarge port is provided on the more downstream side of the swirl flowthan the liquid discharge port and between the interior wall of theliquid discharge chamber and the reverse flow prevention wall, theliquid adhering to the interior wall of the air-oil separation chamberand the liquid discharge chamber can be guided into the liquid dischargeport without any problem.

According to the fifth aspect of the invention, since the reverse flowprevention wall formed integrally with the liquid discharge chamberextends from the liquid discharge chamber substantially in parallel withthe axis of the air-oil separation chamber, the reverse flow preventionwall can be formed without increasing the number of components.Moreover, since the reverse flow prevention wall can be formed at thesame time as the air-oil separation chamber and the liquid dischargechamber are formed, the formation of the reverse flow prevention wallcan be facilitated.

What is claimed is:
 1. A centrifugal air-oil separator, comprising: asubstantially cylindrical air-oil separation chamber and a substantiallyconical liquid discharge chamber which are integrated with each otherand are disposed horizontally; and an air-oil separation plate disposedbetween a gas supply port communicating with said air-oil separationchamber and a gas discharge port communicating with said liquiddischarge chamber, wherein a liquid discharge port is provided at alowest portion between a largest-diameter portion of said liquiddischarge chamber and said air-oil separation plate.
 2. The centrifugalair-oil separator as set forth in claim 1, wherein a reverse flowprevention wall is disposed above said liquid discharge port.
 3. Thecentrifugal air-oil separator as set forth in claim 2, wherein saidreverse flow prevention wall is provided at a lower portion of saidliquid discharge chamber in such a manner as to follow a swirl flow, andis connected to an interior wall of said liquid discharge chamber on amore upstream side of said swirl flow than said liquid discharge port.4. The centrifugal air-oil separator as set forth in claim 3, wherein aliquid discharge passage is provided on a more downstream side of saidswirl flow than said liquid discharge port between the interior wall ofsaid liquid discharge chamber and said reverse flow prevention wall. 5.The centrifugal air-oil separator as set forth in claim 1, wherein saidreverse flow prevention wall is formed integrally with said liquiddischarge chamber in such a manner as to extend from said liquiddischarge chamber substantially in parallel with an axis of said air-oilseparation chamber.
 6. The centrifugal air-oil separator as set forth inclaim 1, wherein said oil-air separation plate is attached to a gasdischarge pipe forming said gas discharge port.